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Iceland Mag

Geology

Öræfajökull: Iceland's second deadliest volcano

By Staff

  • Seen from the air The cauldron that formed last winter in the ice cap of the volcano's crater can be seen clearly in this photo. Photo/Ágúst J. Magnússon

  • Hvannadalshnjúkur peak Seen from Skaftafell in Vatnajökull national park. Photo/Vilhelm

  • Location of Öræfajökull The southernmost part of Vatnajökull glacier. Photo/Loftmyndir.is

It seems fitting that Iceland's tallest peak also Hvannadalshnjúkur is located in one of Iceland‘s deadliest volcanoes. For more than 250 years Öræfajökull has been lying dormant, hidden beneath the southernmost part of the ice cap of Vatnajökull glacier. In recent months this monster has been showing growing levels of activity.

Read more: Magma movements in Öræfajökull volcano a clear sign of growing activity 

The tallest peak in Öræfajökull is Hvannadalshnjúkur peak, standing at 2,110 m (6,921 ft) above sea-level, Hvannadalshnjúkur is a peak in the NW part of the ridge surrounding the volcano's crater.

The volcano is covered with an ice cap which forms the southernmost part of Vatnajökull glacier. Öræfajökull glacier has several outlet glaciers, including Svínafellsjökull and Fjallsjökull who empty into two of the most popular glacial lagoons in Iceland. 

"The Glacier of the Wastes"
Öræfajökull derives its name from the surrounding region, Öræfi. The Icelandic word öræfi can mean either uninhabitable wasteland or land which lacks harbor, which means that Öræfajökull could be translated as the "Glacier of the Wastes".

However, it was not always so. During the first centuries of Icelandic history Öræfajökull was named Hnappafellsjökull and the prosperous farmlands in its foothills were called Litla-Hérað. Then in 1362 Öræfajökull erupted in a terrifying steam-blast eruption, similar to the 1883 Krakatoa eruption and the 1980 Mount St. Helens eruption, causing widespread destruction and death. The entire region was laid to waste. It is believed that the eruption destroyed 20-40 farms in the surrounding area, killing all inhabitants and livestock.

Steam-blast eruptions are also known as phreatic or ultravolcanian eruptions, steam-blast eruptions occur when magma meets groundwater, creating superheated steam in a near-instantaneous evaporation. The resulting explosion can eject enormous quantities of ash, rock and volcanic material into the air. The material is then deposited over surrounding areas, while finer particles are ejected high into the atmosphere.

Only the 1783-1784 Lakagígar eruption, which killed 20% of the population of Iceland and 50-80% of livestock, has been more deadly.

Dormant for more than 250 years
Öræfajökull is believed to erupt once every few hundred years. In addition to the massive 1362 eruption it has erupted only once since Iceland was settled. A smaller eruption took place in 1727 did not cause significant devastation. Outburst floods from the glacier, caused by the sudden melting of ice, washed away two farms, killing three people.

The exact death toll in the 1362 Öræfajökull eruption is not known. It destroyed one of the most prosperous farmland regions in South Iceland, killing all inhabitants and livestock. The eruption deposited 10 cubic kilometers (2.4 cubic miles) of volcanic material over the fields and farms in the region, making the area uninhabitable for decades.

The 1362 eruption is considered to be the largest tepthra eruption in the world in the last 1000 years.

Waking up from a slumber
In 2016 geologists began detecting changes in the area. Seismic activity began picking up, with several sharp tremors and earthquake swarms, rising geothermal activity and significant uplift have also been detected. These developments all point to magma pushing its way into the upper layers of the earths crust. Since the activity began the Icelandic Meteorological Office has stepped up its monitoring of the volcano.

Read more: The Ice cauldron in Öræfajökull continues to deepen, new photos from NASA show

To date the magma movements are believed to be relatively small, significantly smaller than what was seen in the lead up to the 2010 Eyjafjallajökull eruption. However, it is large enough to cause the creation of a new powerful geothermal area in the volcano's caldera, capable of melting deep cauldrons in the ice cap.

Popular tourist destinations could be affected
An eruption in Öræfajökull could have dramatic consequences: Two of Iceland's most popular tourist destinations are located in the foothills of Öræfajökull: Skaftafell visitor center in Vatnajökull National Park and Jökulsárlón glacier lagoon. An estimated one million people visit Jökulsárlón annually.

But volcanoes move very slowly, and it can take years, even decades, for a volcano to work itself up into an eruption. Volcanoes are also known to stir and tremble, only to return to centuries of slumber. Too little is known about the behavior of Öræfajökull to interpret the activity of the past couple of years.

However, geophysicists have pointed out that the behavior of Öræfajökull now is similar to activity in Eyjafjallajökull volcano in 1998. Twelve years later (in 2010) Eyjafjallajökull finally erupted.

Emergency evacuation plan
The Icelandic Civil Protection agency is not taking any chances: An uncertainty phase has been declared for the area. The Icelandic Civil Protection Agency estimates that it will have a 20 minute warning before any eruption in the glacier. In case of an eruption people are asked to proceed according to the Emergency Evacuation Plan:

Anyone located east of Kvíá river should proceed east toward Jökulsárlón glacier lagoon and the town of Höfn.

Anyone west of Freysnes farm and rest stop should proceed west toward the town of Kirkjubæjarklaustur.

People caught between these two points should proceed to the following farms:

Anyone east of Fagurhólsmýri farm is to proceed to the farm Hnappavellir II.

Anyone west of Fagurhólsmýri should either proceed to Hof I or Svínafell II, depending on which one is closer.

Catastrophic mountain collapse
If the threat of an eruption in Öræfajökull wasn't enough, a second major natural disaster is looming in its foothills: Catastrophic mountain collapse.

Read more: Popular SE Iceland glacial lagoon a ticking time bomb: Catastrophic mountain collapse looms

Due to global climate change the outlet glaciers of Öræfajökull have shrunk and retreated. One of these is Svínafellsjökull glacier, which empties into a small but beautiful lagoon. As the glacier retreats it exposes the sheer cliffs of mount Svínafell, while at the same time removing support for the mountain.

A deep and extensive fracture system has emerged in the slopes of Svínafell, as one square kilometer (250 acres) have begun to seperate from the rest of the mountain. Scientists estimate that up to 60 million m3 (165 million cubic feet) of material could either collapse all at once or in successive rock falls.

Visitors are urged not to og hiking on Svínafellsjökull and to limit their time at the glacier lagoon: Just like an eruption catastrophic mountain collapse would no doubt be a dramatic sight, but it is equally true that standing too close to one could prove fatal!

Emergency Evacuation Plan for Öræfajökull

In the case of an eruption Emergency Evacuation Plan for Öræfajökull, Photo/Icelandic Civil Protection Agency

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